It is important to recognize that there is a close relationship
between water source areas in the upland watershed, transport
areas in the foothill and terrace, and discharge areas in the lowlands
of the Khlong U-Taphao Basin. These areas are inter-connected
throughout the basin by the U-Taphao River and its tributaries,
hence disturbances in upstream areas can prove detrimental
downstream where Hat Yai Municipality is located (Tanavud et al.,
2001a). For instance, deforestation of the mountainous upper
watershed can increase the physical magnitude of the flood hazard
and contribute to downstream flood damage (WHO, 2002). The
hazard of flooding is known to be governed by the condition of
upland ecosystems as well as those in the lowlands which increase
the hazard or vulnerability. Measures that address flooding that
poses a risk to the municipality downstream therefore need to be
adopted in the context of the watershed basis. To identify and
implement the most effective responses to flood hazards, risk
assessment based on a hazard and vulnerability analysis needs to
be made. Our study therefore aimed to assess the flood risk in Hat
Yai Municipality in order that adequate, successful risk reduction
schemes can be identified and measures taken to prevent future
disasters.